Between Corpus and Dictionary Adam Kilgarriff Lexical Computing Ltd Lexicography MasterClass Ltd Universities of Leeds, Sussex

Between Corpus and Dictionary

Adam KilgarriffLexical Computing Ltd

Lexicography MasterClass LtdUniversities of Leeds, Sussex

Szeged, Jan 2008 Kilgarriff, Global WordNet 2

What is a word sense?


Preliminaries

What is language? What is meaning?


What is language?


What is language? In our heads


What is language? In our heads In texts and sound signals


What is language? In our heads In texts and sound signals Both


Methodology Study language in our heads

Introspection Semantic analysis Experiments with human subjects

“rationalist” (Leibniz, Chomsky) Problems: coverage, arbitrariness


Methodology Study text

“empiricist” (Locke, Hume)

Physics: forces, matter Chemistry: chemicals, bonds Language: text, speech

signals


It goes against the grain

What is important about a sentence? its meaning

Corpus methodology: Throw away individual sentence

meaning Find patterns


Empiricist linguistics A new way to find out about

language 15 years of rapid ascent

Computers Corpora

bigger and bigger data sets available Language technology tools

lemmatizers, POS-taggers, parsers, machine learning for pattern finding


Rationalists vs empiricists in the age of the web

semantic web vs Google?


What are you?

Temperament Complementary/alternatives

Barbu and Poesio, Keller and Lapata: comparisons, evaluations

(AK: current research project)


What is meaning?

Fregean Gricean


Gottlob Frege (1848-1925) Founder of modern logic Truth values

The sentence “grass is green” is true if and only if grass is green (Tarski)

Meanings of words, phrases are such that:

Put them together in a sentence State basic facts Sentence computes to ‘true’ if sentence is

true, ‘false’ if it is false


Gottlob Frege (1848-1925)

Formal semantics Sparkling analyses for quantifiers,

connectives Montague semantics

Foundations for maths, databases, ontologies …


H. P. Grice (1913-1988)

An agent means something by an utterance if and only if they intended the utterance to produce some effect in an audience by means of the recognition of this intention.

Dictionary of Philosophy of Mind, http://philosophy.uwaterloo.ca


Meaning is something you do

Basis of meaning is Meaning event Speaker’s intention Speaker’s expectation of

interpretation of hearer (messy, hard)


Strawson commentary (1970s)For the sake of a label, we might call it the

conflict between the theorists of communication-intention and the theorists of formal semantics. […] A struggle on what seems to be such a central issue in philosophy should have something of a Homeric quality; and a Homeric struggle calls for gods and heroes. I can at least, though tentatively, name some living captains and benevolent shades: on the one side, say, Grice, Austin, and the later Wittgenstein; on the other, Chomsky, Frege, and the earlier Wittgenstein.


Battle of the two Adams?


Relevance to word senses

Fregean Supports reasoning Builds on well-defined word-meanings

Identifying word meanings: can’t help Fall back on Grice


Fauconnier and Turner

“linguistics expressions prompt for meanings rather than express meanings”

(AK chapter, Agirre and Edmonds WSD book)


Preliminaries over

What is a word sense


The lexicographers

They create them Methods

Introspection Other dictionaries Corpus

Atkins, Hanks, Krishnamurthy


What is a word sense (1)

SFIP Sufficiently frequent insufficiently

predictable (a glass of) whisky x (a glass of) tequila



homonymy

analogy polysemy rules

collocation



A cluster Of instances of use

Operationalised as: corpus lines Clustered by lexicographers










What is a word sense (3) A cluster

Of instances of use Operationalised as: corpus lines

Clustered by lexicographers Makes sense of

Overlapping senses Different dictionaries, different senses Lumping and splitting


I don’t believe in word senses

Believe in: resurrection ghost witch vampire god

miracle fairy Philosophy:

Ontological commitment (same meaning different register)

“good entities to build belief systems on”


But I’m an NLP person

Automatic clustering? Inspiration:

Hindle 1991, Schütze 1993, Grefenstette 1993, Lin 1999

You can get semantic sense from corpora+stats


First attempt

Longman 1994 Abject failure

No grammar Corpus too small and noisy Naïve clustering Useless programmer


Collocations Easy

Most words don’t go with most other words

Then build on what we can do well (metaphor, analogy, homonymy,

rules: all much harder)


The Sketch Engine 2003: programmer problem solved Corpora

More available Build big clean ones from web

Grammar POS-taggers/lemmatisers available Shallow regexp grammars if no full parser

Stats: progress (Lin, Curran, Evert …)


demo


Clustering

Word sketch Collocates organised by grammar

Dictionary Collocates (and other things)

organised by meaning How to re-organise

Three phases


Semi-automatic dictionary drafting (SADD) Automatic clustering of collocates

Propose senses Iterate:

Lexicographer input Confirm/reject/edit sense inventory Assigns collocates / corpus lines to senses

WSD Uses seeds to build full WSD for word Find more collocates for each sense

XML dictionary entry Load into dictionary-editing tool


Atkins method for bilingual lexicography Analyse source language

From corpus List all expressions that might possibly have

a non-predictable translation Very fine grained Lots of collocations

target-language-neutral; re-usable Translate Edit to finalise dictionary


New English-Irish Dictionary

Irish: Gaelic language, some native speakers,

culturally important for Ireland Project

To replace dictionary from 1950s Government-funded project Lexicography MasterClass (Atkins

Rundell Kilgarriff) designed project in 2003


English analysis for NEID

New project, 1st Feb 2008- late 2010 Contractor: Lexicography

MasterClass 12 lexicographers Plan

Test SADD If viable, use it on industrial scale


demo2

http://corpora.fi.muni.cz/sadd/


Thank you

Sketch Engine: http://www.sketchengine.co.uk

Lexicom workshop Pre-Euralex, 10-15 July, Barcelona

http://www.iula.upf.edu/agenda/lexicom Pre-CICLING, Mexico, Feb 2009

Documents

Between Corpus and Dictionary Adam Kilgarriff Lexical Computing Ltd Lexicography MasterClass Ltd Universities of Leeds, Sussex